Macroscale analyses suggest invasive plant impacts depend more on the composition of invading plants than on environmental context

Authors: BEAURY, EVELYN - University Of Massachusetts, Amherst; SOFAER, HELEN - Us Geological Survey (USGS); EARLY, REGAN - University Of Exeter; PEARSE, IAN - Us Geological Survey, Fort Collins Science Center; Blumenthal, Dana; CORBIN, JEFFREY - Union College; DIEZ, JEFFREY - University Of Oregon; DUKES, JEFFREY - Purdue University; BARNETT, DAVID - Battelle Memorial Institute; IBANEZ, INES - University Of Massachusetts

Submitted to: Proceedings of the National Academy of Sciences (PNAS)
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/11/2023
Publication Date: 8/29/2023
Citation: Beaury, E.M., Sofaer, H.R., Early, R., Pearse, I.S., Blumenthal, D.M., Corbin, J.D., Diez, J., Dukes, J.S., Barnett, D.T., Ibanez, I. 2023. Macroscale analyses suggest invasive plant impacts depend more on the composition of invading plants than on environmental context. Proceedings of the National Academy of Sciences (PNAS). 32(11):1964-1976. https://doi.org/10.1111/geb.13749.
DOI: https://doi.org/10.1111/geb.13749

Interpretive Summary: Mitigating impacts of invasive species requires an understanding where those impacts are most severe. Using more than 20,000 vegetation surveys from across the U.S., we asked how characteristics of invaded plant communities influence the impacts of invasion on native plant diversity. Highly invaded plant communities had fewer native plant species and reduced variation in abundance between species, suggesting that rare species can be lost while dominant native plants decline in abundance. Native diversity declined the most with invasion in areas with high productivity and high anthropogenic impact, as well as areas invaded by a dominant invasive plant with multiple other non-native species present. These results will help policy makers and land managers focus management efforts on the most vulnerable native ecosystems.

Technical Abstract: Native biodiversity is continuously threatened by the spread of non-native invasive species. Many studies have demonstrated that these invasions reduce local biodiversity, but the magnitude of this impact can vary considerably. Here, we aimed to understand what macroecological characteristics of recipient communities affect their vulnerability to invasive plant impacts. Using more than 20,000 vegetation surveys from ecosystems across the U.S., we asked how non-native plant cover interacts with the conditions of recipient communities to determine invasion impact on native plant richness, diversity, and evenness. We hypothesized that invasive plant impacts vary with productivity, human modification, and the richness and evenness of the invading plant community. Across the U.S., highly invaded plant communities had lower native plant richness and diversity but higher evenness, suggesting that rare species can be lost while dominant native plants decline in abundance. We also found that as non-native cover increased, native communities showed the strongest declines in diversity in areas with high productivity and high anthropogenic impact, as well as areas invaded by a dominant invasive plant with multiple other non-native species present. Our macroscale study suggests that invasive plant impacts are a function of invader abundance and the conditions of recipient native communities. Focusing management on the most vulnerable native ecosystems could therefore reduce the negative impacts associated with plant invasions.